Kaidan Alenko

Kaidan Alenko was first introduced in Mass Effect as your first teammate. He is a Biotic that is equipped with an "L2" biotic implant that allows his powers to spike higher than most other biotic soldiers at the expense of painful migranes. He is a possible romantic interest for a female Shepard in the original Mass Effect and he can also die during the mission on Virmire.

In Mass Effect 2, he makes an appearance on Horizon (provided he survives the events of Mass Effect), but he does not join your party.

Kaidan returns in Mass Effect 3 (providing he survived the Virmire mission in Mass Effect). Kaidan before the events of Mass Effect 3 has recently been promoted to Major and commands the 1st Special Operations Biotic Company. In Mass Effect 3 Counciller Udina offers Kaidan the chance to become a council spectre, which he accepts making him the second human (behind Shepard) in history to given spectre status. Kaidan returns in Mass Effect 3 as a squadmate and is romancable for male and female Shepards.